1. Field of the Invention
The present invention relates to a device for the reverse-twisting of stranding elements.
2. Description of the Prior Art
The term "stranding elements" as used in the sense of the invention refers to individual elements which make up the cores of cables. The elements may be optical, electrical, or any other kind of conductors which make up the cores of optical, electrical or other type of cable. Stranding elements can also be elements of a higher order, which already encompass several individual stranding elements. Higher order elements are for example pairs, fours, bundles, etc. The stranding elements can also be plastic filaments or bare metal wires which are used as the concentric protective conductors of power line cables or to shield high-voltage cables or telecommunication cables, for example.
During stranding of stranding elements, reverse-twisting, which periodically changes the twist direction of the stranding elements, provides advantages over stranding processes wherein the twist direction remains the same. For example, if reverse-twisting is not used, a rotating spool discharge for the stranding elements is needed, which only allows the stranding elements to be manufactured in limited lengths. In contrast, reverse-twisting offers the possibility of continuous manufacture of the stranding elements at high discharge speeds.
One device which is particularly well-suited for reverse-twisting of stranding elements is disclosed in German document DE-OS 42 26 514, wherein the stranding elements are subjected to extremely low friction during the twisting process, in contrast to another known device disclosed in German document DE-AS 22 62 705. The advantages provided by the device disclosed in German document DE-OS 42 26 514 are provided by using holding elements, preferably holding disks, which have a low mass, so that no significant additional masses must be moved during the twisting of the stranding elements, even when a large number of such holding disks are used. Because of the low rotational moment of inertia of the holding disks, the reversing times of the stranding can be kept very short. Contamination of the holding disks or their passage holes is eliminated, dust particles or water scale (from cooling water) cannot be deposited on the holding disks, in contrast to known guide hoses used in other prior art devices. The stranding conditions provided by the device disclosed in German document DE-OS 42 26 514 can therefore be considered constant.